Докажите ! sin2a(sin2a+sin2b) +cos2a(cos2a+cos2b)=2cos(в - вопрос №166042222222 от Salahaddin001 29.06.2021 22:51

Question

Алгебра: Докажите ! sin2a(sin2a+sin2b) +cos2a(cos2a+cos2b)=2cos(в квадрате) (a-b)

Salahaddin001 · Answer

sin2a(sin2a+sin2b) +cos2a(cos2a+cos2b)=sin²2a + sin2asin2b + cos²2a + cos2acos2b=(sin²2a+cos²2a)+sin2asin2b +cos2acos2b=1+cos(2a-2b)=1+cos2(a-b)= =1+cos²(a-b) - sin²(a-b)=2cos²(a-b)...